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Inhibition of melanogenesis by jineol from Scolopendra subspinipes mutilans via MAP-Kinase mediated MITF downregulation and the proteasomal degradation of tyrosinase

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ABSTRACT

In this study, the authors investigated the anti-melanogenic effects of 3,8-dihydroxyquinoline (jineol) isolated from Scolopendra subspinipes mutilans, the mechanisms responsible for its inhibition of melanogenesis in melan-a cells, and its antioxidant efficacy. Mushroom tyrosinase activities and melanin contents were determined in melan-a cells, and the protein and mRNA levels of MITF, tyrosinase, TYRP-1, and TYRP-2 were assessed. Jineol exhibited significant, concentration-dependent antioxidant effects as determined by DPPH, ABTS, CUPRAC, and FRAP assays. Jineol significantly inhibited mushroom tyrosinase activity by functioning as an uncompetitive inhibitor, and markedly inhibited melanin production and intracellular tyrosinase activity in melan-a cells. In addition, jineol abolished the expressions of tyrosinase, TYRP-1, TYRP-2, and MITF, thereby blocking melanin production and interfering with the phosphorylations of ERK1/2 and p38. Furthermore, specific inhibitors of ERK1/2 and p38 prevented melanogenesis inhibition by jineol, and the proteasome inhibitor (MG-132) prevented jineol-induced reductions in cellular tyrosinase levels. Taken together, jineol was found to stimulate MAP-kinase (ERK1/2 and p38) phosphorylation and the proteolytic degradation pathway, which led to the degradations of MITF and tyrosinase, and to suppress the productions of melanin.

No MeSH data available.


Inhibitory effects of jineol on mushroom tyrosinase activity.(A) Different concentrations of jineol or arbutin were incubated with the same units of mushroom tyrosinase. Following incubation, amounts of dopachrome produced were determined at 490 nm spectrophotometrically. (B) Effects of jineol on the monophenolase activity of tyrosinase. Enzyme activity was tested in the presence of L-tyrosine, as substrate. (C) Lineweaver-Burk plot of mushroom tyrosinase in the presence of jineol. Results are expressed as mean values of 1/V, as inverses of increases in absorbance at 490 nm/minute (ΔA490 per minute), and as the means of three independent tests at different L-tyrosine concentrations. Results are presented as the means ± SDs of three experiments. *P < 0.05, **P < 0.01, versus non-treated controls, Student’s t-test. Arb: Arbutin.
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f3: Inhibitory effects of jineol on mushroom tyrosinase activity.(A) Different concentrations of jineol or arbutin were incubated with the same units of mushroom tyrosinase. Following incubation, amounts of dopachrome produced were determined at 490 nm spectrophotometrically. (B) Effects of jineol on the monophenolase activity of tyrosinase. Enzyme activity was tested in the presence of L-tyrosine, as substrate. (C) Lineweaver-Burk plot of mushroom tyrosinase in the presence of jineol. Results are expressed as mean values of 1/V, as inverses of increases in absorbance at 490 nm/minute (ΔA490 per minute), and as the means of three independent tests at different L-tyrosine concentrations. Results are presented as the means ± SDs of three experiments. *P < 0.05, **P < 0.01, versus non-treated controls, Student’s t-test. Arb: Arbutin.

Mentions: Mushroom tyrosinase is widely used as the target enzyme for the screening of potential inhibitors of melanogenesis, and thus, to determine whether jineol has anti-melanogenic activity, we first examined its effect on mushroom tyrosinase. The use of L-tyrosine and L-DOPA as substrates enabled us to distinguish between the ability of the compound to inhibit the o-hydroxylation of tyrosine and its further oxidation to o-diquinone. Jineol dose-dependently inhibited mushroom tyrosinase activity with an IC50 of 39.46 ± 0.01 and 50.35 ± 0.05 for the substrates L-tyrosine and L-DOPA, respectively, whereas arbutin (a well-known tyrosinase inhibitor) had an IC50 of 296.63 ± 0.01 as L-tyrosine is being a substrate (Fig 3A). Furthermore, the effects of increasing concentrations of jineol on the monophenolase and diphenolase activated forms of tyrosinase are shown in Supplementary Fig. S1.


Inhibition of melanogenesis by jineol from Scolopendra subspinipes mutilans via MAP-Kinase mediated MITF downregulation and the proteasomal degradation of tyrosinase
Inhibitory effects of jineol on mushroom tyrosinase activity.(A) Different concentrations of jineol or arbutin were incubated with the same units of mushroom tyrosinase. Following incubation, amounts of dopachrome produced were determined at 490 nm spectrophotometrically. (B) Effects of jineol on the monophenolase activity of tyrosinase. Enzyme activity was tested in the presence of L-tyrosine, as substrate. (C) Lineweaver-Burk plot of mushroom tyrosinase in the presence of jineol. Results are expressed as mean values of 1/V, as inverses of increases in absorbance at 490 nm/minute (ΔA490 per minute), and as the means of three independent tests at different L-tyrosine concentrations. Results are presented as the means ± SDs of three experiments. *P < 0.05, **P < 0.01, versus non-treated controls, Student’s t-test. Arb: Arbutin.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5385534&req=5

f3: Inhibitory effects of jineol on mushroom tyrosinase activity.(A) Different concentrations of jineol or arbutin were incubated with the same units of mushroom tyrosinase. Following incubation, amounts of dopachrome produced were determined at 490 nm spectrophotometrically. (B) Effects of jineol on the monophenolase activity of tyrosinase. Enzyme activity was tested in the presence of L-tyrosine, as substrate. (C) Lineweaver-Burk plot of mushroom tyrosinase in the presence of jineol. Results are expressed as mean values of 1/V, as inverses of increases in absorbance at 490 nm/minute (ΔA490 per minute), and as the means of three independent tests at different L-tyrosine concentrations. Results are presented as the means ± SDs of three experiments. *P < 0.05, **P < 0.01, versus non-treated controls, Student’s t-test. Arb: Arbutin.
Mentions: Mushroom tyrosinase is widely used as the target enzyme for the screening of potential inhibitors of melanogenesis, and thus, to determine whether jineol has anti-melanogenic activity, we first examined its effect on mushroom tyrosinase. The use of L-tyrosine and L-DOPA as substrates enabled us to distinguish between the ability of the compound to inhibit the o-hydroxylation of tyrosine and its further oxidation to o-diquinone. Jineol dose-dependently inhibited mushroom tyrosinase activity with an IC50 of 39.46 ± 0.01 and 50.35 ± 0.05 for the substrates L-tyrosine and L-DOPA, respectively, whereas arbutin (a well-known tyrosinase inhibitor) had an IC50 of 296.63 ± 0.01 as L-tyrosine is being a substrate (Fig 3A). Furthermore, the effects of increasing concentrations of jineol on the monophenolase and diphenolase activated forms of tyrosinase are shown in Supplementary Fig. S1.

View Article: PubMed Central - PubMed

ABSTRACT

In this study, the authors investigated the anti-melanogenic effects of 3,8-dihydroxyquinoline (jineol) isolated from Scolopendra subspinipes mutilans, the mechanisms responsible for its inhibition of melanogenesis in melan-a cells, and its antioxidant efficacy. Mushroom tyrosinase activities and melanin contents were determined in melan-a cells, and the protein and mRNA levels of MITF, tyrosinase, TYRP-1, and TYRP-2 were assessed. Jineol exhibited significant, concentration-dependent antioxidant effects as determined by DPPH, ABTS, CUPRAC, and FRAP assays. Jineol significantly inhibited mushroom tyrosinase activity by functioning as an uncompetitive inhibitor, and markedly inhibited melanin production and intracellular tyrosinase activity in melan-a cells. In addition, jineol abolished the expressions of tyrosinase, TYRP-1, TYRP-2, and MITF, thereby blocking melanin production and interfering with the phosphorylations of ERK1/2 and p38. Furthermore, specific inhibitors of ERK1/2 and p38 prevented melanogenesis inhibition by jineol, and the proteasome inhibitor (MG-132) prevented jineol-induced reductions in cellular tyrosinase levels. Taken together, jineol was found to stimulate MAP-kinase (ERK1/2 and p38) phosphorylation and the proteolytic degradation pathway, which led to the degradations of MITF and tyrosinase, and to suppress the productions of melanin.

No MeSH data available.